1. Technical Field
The disclosure relates to a method for manufacturing a semiconductor device, and more specifically, to a method for manufacturing a semiconductor device which includes a planarization process including a first and second Chemical Mechanical Polishing (CMP) processes using CeO2 and SiO2 slurries to improve uniformity of the CMP process, thereby securing yield and reliability of devices.
2. Description of the Related Art
As the degree of integration of semiconductor devices increases, planarization processes using CMP are generally performed.
The CMP process, which is necessarily performed to planarize contact plugs and insulating films of semiconductor devices, planarizes the surface of a wafer to be processed using frictional force of a slurry and a polishing pad. In the CMP process, consumable materials such as a backing film slurry, a diamond conditioner, and a retainer ring are used, and the slurry accounts for the greatest expense. Since scratches in a semiconductor device are generated by agglomeration phenomena of abrasives included in the slurry or by abrasives having large particles (greater than 0.1 μm), a slurry filter may be required to remove such scratches.
The CMP process causes dishing phenomena by pressure between the wafer surface to be processed and the polishing pad and by residual abrasive in the slurry. As a result, in order to reduce such phenomena, dummy patterns are properly designed and/or a method of increasing line speed and decreasing pressure of the CMP process is applied. Additionally, in order to obtain desired planarization in the CMP process, which causes the dishing phenomena, whole films might be formed thickly and then the CMP processing amount is increased, which results in high cost and low efficiency.
Furthermore, when polishing speed is increased and polishing pressure is decreased to improve degree of the planarization by the CMP process, non-uniformity in the wafer results, which adversely affects the subsequent contact etching process.
Meanwhile, a slurry mostly including silica (SiO2) as the abrasive has been used in conventional CMP process applied to an insulating film or a landing plug contact. As a result, the polishing speed in edge portions of the wafer is high, so that the semiconductor device is damaged at the edge portions.
Therefore, a CMP method to solve the above-described problems and to improve uniformity of the CMP process has been required in a process for manufacturing a semiconductor device.